Oxygen Sensor broke off

[Falcon3]

2008 4.0 V6

Well I messed up again. I decided to change upstream oxygen sensors at 200k miles out of my own OCD and the desire to prolong my cat life and possibly improve my gas mileage.

The passenger side went amazingly well. Used the offset wrench and every 1/2” extension I own. Once I broke it loose it came out by hand I got the new sensor in and out in 30 mins. Hardest part was unclipping the wire harness.

Driver side started well. The sensor broke loose ok but started getting tighter as I pulled it out. Toward the end it got pretty tight and I pushed a little too hard and POP the sensor broke loose, leaving the last 1 thread and the probe of the sensor in the manifold.

Where do I go from here? New manifold? Which would cost a bunch and require me to break a bunch more rusty bolts loose.

Try to pound the sensor into the exhaust, leaving it to rattle around, and try to clean up the threads?

IÂ’m pretty lost and depressed at my own stupidity right now.

 

[Trumpet]

Actually had a bung break off a exhaust manifold. Brought the car down to my regular shop and they welded a new bung on for short change and got me the right sensor for the bank. (Direct exchange no cost)

So striping a bung or hosing the threads isn't necessarily a huge repair or cost, just need the right tools, or to know the right people.

 

[Bumbo]

I have nothing productive to add other than I like the 2nd response in regards to fixing it.

Few saying come to mind that have been told to me by mechanic friends when I get too excited about preventative maintenance and upgrades…

• If you go looking for trouble, you might just might find it.
• If it isn’t broke, don’t fix it.
• Leave good enough alone.

 

[RonJR]

This will be no help to you, OP, but might help someone else in the future. O2 sensors and spark plugs will often break loose and turn fairly easily, and then tighten up as you continue to back it out. That's your signal to STOP and REVERSE DIRECTION. Turn it back in a half turn or so, and then slowly try removing it again. You'll probably get another 1/2 turn or so out of it before it binds up again. When it does bind up, repeat the reversing procedure. Keep doing that and it will eventually come out without damage.

What is happening is that the threads are galling. Basically the friction is so high that the threads are literally tearing loose from the walls of the manifold and are rolling up inside the bore, causing the plug to wedge tighter and tighter. The harder you pull, the tighter it jams. You can almost never win with brute force - you'll get the same results as the OP or strip all of the threads out of the bore - but the reverse and try again procedure will most often work.

This is a very common problem with steel spark plugs in aluminum heads. I've had plugs in my '94 that took 20 cycles of reverse and try again, but they eventually came out with no damage to the head.

 

[Falcon3]

Thanks for the heads up. I tried the back and forth a bit and it did help, but toward the end it slowed its progress.

I managed to break the sensor tip loose out of the bung. There’s a little bit of sensor thread material in the threads but the threads appear a little damaged but mostly intact.

I’m going to run a thread chaser down the hole and see if I can clean it up enough for the new sensor to take. At 200k this will be the last sensor this rig needs, so I’m just looking to get it in securely.

Hopefully I dodged a big bullet and I have learned my lesson about overzealous preventative maintenance.